Relation of Lifespan to Brain Weight and Body Weight in Mammals

Sacher, George A.

doi:10.1002/9780470715253.ch9

Cited by 70 publications

(47 citation statements)

References 8 publications

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“…with mass-specific metabolic rate, animals with a high mass-specific metabolic rate should have a shorter life span than species with a low mass-specific metabolic rate (Pearl, 1928;Harman, 1955;Sacher, 1959). Evidence for this free-radical theory of ageing suggested by Harman (Harman, 1955) has been found in many empirical studies.…”

Section: Introductionmentioning

confidence: 94%

Inflammatory challenge increases measures of oxidative stress in a free-ranging, long-lived mammal

Schneeberger

Czirják

Voigt

2013

Journal of Experimental Biology

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SUMMARYOxidative stress -the imbalance between reactive oxygen species (ROS) and neutralising antioxidants -has been under debate as the main cause of ageing in aerobial organisms. The level of ROS should increase during infection as part of the activation of an immune response, leading to oxidative damage to proteins, lipids and DNA. Yet, it is unknown how long-lived organisms, especially mammals, cope with oxidative stress. Bats are known to carry a variety of zoonotic pathogens and at the same time are, despite their high mass-specific basal metabolic rate, unusually long lived, which may be partly the result of low oxidative damage of organs. Here, we asked whether an immune challenge causes oxidative stress in free-ranging bats, measuring two oxidative stress markers. We injected 20 short-tailed fruit bats (Carollia perspicillata) with bacterially derived lipopolysaccharide (LPS) and 20 individuals with phosphate-buffered saline solution (PBS) as a control. Individuals injected with LPS showed an immune reaction by increased white blood cell count after 24 h, whereas there was no significant change in leukocyte count in control animals. The biological antioxidant potential (BAP) remained the same in both groups, but reactive oxygen metabolites (ROMs) increased after treatment with LPS, indicating a significant increase in oxidative stress in animals when mounting an immune reaction toward the inflammatory challenge. Control individuals did not show a change in oxidative stress markers. We conclude that in a long-lived mammal, even high concentrations of antioxidants do not immediately neutralise free radicals produced during a cellular immune response. Thus, fighting an infection may lead to oxidative stress in bats.

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Section: Introductionmentioning

confidence: 94%

Inflammatory challenge increases measures of oxidative stress in a free-ranging, long-lived mammal

Schneeberger

Czirják

Voigt

2013

Journal of Experimental Biology

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“…This is the second area where 'technical benefits' played an important role in humans; improvements of weapons would have given some groups a great advantage over others (see also Flynn et al 2005). and Deaner et al (2003) revisit the correlation between slow life history and large brain size (see Sacher 1959;Sacher & Staffeldt 1974;Pagel & Harvey 1988, 1989. Their new analysis, based on mammalian orders, revealed a weak relationship between EQs (observed brain size/expected based on body size) and longevity quotients (observed maximum lifespan/expected maximum lifespan based on body size) that became highly significant once the outlier Chiroptera were removed.…”

Section: The Social Competition Hypothesismentioning

confidence: 99%

Dolphin social intelligence: complex alliance relationships in bottlenose dolphins and a consideration of selective environments for extreme brain size evolution in mammals

Connor

2007

Phil. Trans. R. Soc. B

227

229

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Bottlenose dolphins in Shark Bay, Australia, live in a large, unbounded society with a fission-fusion grouping pattern. Potential cognitive demands include the need to develop social strategies involving the recognition of a large number of individuals and their relationships with others. Patterns of alliance affiliation among males may be more complex than are currently known for any non-human, with individuals participating in 2-3 levels of shifting alliances. Males mediate alliance relationships with gentle contact behaviours such as petting, but synchrony also plays an important role in affiliative interactions. In general, selection for social intelligence in the context of shifting alliances will depend on the extent to which there are strategic options and risk. Extreme brain size evolution may have occurred more than once in the toothed whales, reaching peaks in the dolphin family and the sperm whale. All three 'peaks' of large brain size evolution in mammals (odontocetes, humans and elephants) shared a common selective environment: extreme mutual dependence based on external threats from predators or conspecific groups. In this context, social competition, and consequently selection for greater cognitive abilities and large brain size, was intense.

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“…Ever since Sacher (1959) first pointed to an interspecific correlation between brain size and life history variables in a sample of mammals, numerous studies have revisited this subject, especially for primates (Sacher and Staffeldt 1974;Sacher 1975Sacher , 1978Harvey and Clutton-Brock 1985;Harvey et al, 1987;Austad and Fischer 1992;Allman et al 1993;Allman 1995;Hakeem et al 1996;Allman and Hasenstaub 1999;Barton 1999;Ross and Jones 1999;Judge and Carey 2000a;Deaner et al 2003;Ross 2003Ross , 2004Leigh 2004). The existence of this evolutionary relationship has substantial implications for the study of human evolution.…”

Section: Introductionmentioning

confidence: 99%

Life history costs and benefits of encephalization: a comparative test using data from long-term studies of primates in the wild

Barrickman

Bastian

Isler

et al. 2008

Journal of Human Evolution

182

168

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The correlation between brain size and life history has been investigated in many previous studies, and several viable explanations have been proposed. However, the results of these studies are often at odds, causing uncertainties about whether these two character complexes underwent correlated evolution. These disparities could arise from the mixture of wild and captive values in the datasets, potentially obscuring real relationships and from differences in the methods of controlling for phylogenetic nonindependence of species values. This paper seeks to resolve these difficulties by (1) proposing an overarching hypothesis that encompasses many of the previously proposed hypotheses; (2) testing the predictions of this hypothesis using rigorously compiled data and utilizing multiple methods of analysis. Our hypothesis is that the adaptive benefit of increased encephalization is an increase in reproductive lifespan or efficiency, which must be sufficient to outweigh the costs due to growing and maturing the larger brain. These costs and benefits are directly reflected in the length of life history stages. We tested this hypothesis on a wide range of primate species. Our results demonstrate that encephalization is significantly correlated with prolongation of all stages of developmental life history except the lactational period, and is significantly correlated with an extension of the reproductive lifespan. These results support the contention that the link between brain size and life history is caused by a balance between the costs of growing a brain and the survival benefits the brain provides, and specifically the slowing of life history during human evolution is caused by increased encephalization. 1Life history costs and benefits of encephalization: a comparative test using data from long-term studies of primates in the wild Nancy L. Barrickman AbstractThe correlation between brain size and life history has been investigated in many previous studies, and several viable explanations have been proposed. However, the results of these studies are often at odds, causing uncertainties about whether these two character complexes underwent correlated evolution. These disparities could arise from the mixture of wild and captive values in the datasets, potentially obscuring real relationships and from differences in the methods of controlling for phylogenetic nonindependence of species values. This paper seeks to resolve these difficulties by (1) proposing an overarching hypothesis that encompasses many of the previously proposed hypotheses; (2) testing the predictions of this hypothesis using rigorously compiled data and utilizing multiple methods of analysis. Our hypothesis is that the adaptive benefit of increased encephalization is an increase in reproductive lifespan or efficiency, which must be sufficient to outweigh the costs due to growing and maturing the larger brain. These costs and benefits are directly reflected in the length of life history stages. We tested this hypothesis on a wide range of pr...

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Relation of Lifespan to Brain Weight and Body Weight in Mammals

Cited by 70 publications

References 8 publications

Inflammatory challenge increases measures of oxidative stress in a free-ranging, long-lived mammal

Inflammatory challenge increases measures of oxidative stress in a free-ranging, long-lived mammal

Dolphin social intelligence: complex alliance relationships in bottlenose dolphins and a consideration of selective environments for extreme brain size evolution in mammals

Life history costs and benefits of encephalization: a comparative test using data from long-term studies of primates in the wild

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